Stable detergent composition



United States Patent 3,166,513 STABLE DETERGENT COMPOSITION William G. Mizuno and Thomas M. Oberle, St. Paul, Minn nssignors to Economics Laboratory, Inc., St. Paul, Minn., a corporation of Delaware No Drawing. Filed Apr. 4, 1963, Ser. No. 270,518 5 Claims. (Cl. 252-99) Our invention relates to stable detergent compositions containing both caustic and an organic chlorinating agent especially useful in machine dishwashing. This application is a continuation-in-part of our copending application Serial No. 220,161, filed August 29, 1962, now abandoned.

Machine dishwashing is used in connection with practically all commercial and institutional dining facilities as well as in a rapidly increasing proportion of private homes. It has been the practice in formulating machine dishwashing compositions to use in the main various combinations of inorganic builder salts such as polyphosphates, metasilicates, carbonates and caustic materials such as sodium hydroxide. It also has been recognized that detergency would be enhanced and that germicidal and destaining properties would be imparted to machine dishwashing formulations by incorporation therein of available chlorine containing components. Thus, the use of chlorinating agents such as the polychlorocyanuric acids and their salts, chlorinated trisodium phosphate etc., in combination with phosphate, metasilicate and carbonate builders has also been common practice.

While the use of caustic materials with builder salts and chlorinating agents with builder salts are common, it has been recognized that the incorporation of both caustic materials and chlorinating agents with builder salts in the same formulation results in instability, primarily due to the fact that the caustic material causes moisture absorption thereby promoting decomposition of the chlorinating agent.

Our invention provides stable machine dishwashing compositions containing specific caustic materials and a specific chlorinating agent, i.e., potassium dichlpgpcya-- I nurate, together with convention T' rinating agent being critically sized and blended with the er s ts, the chloother components. Further, the detergent compositions of our invention possess the combined good cleaning qualities of both chlorine and caustic and are superior in cleaning efficiency over presently known machine dishwashing compositions.

The stable compositions of our invention are composed of (A) builder salts in major amount comprising an anhydrous alkali metal phosphate, wherein the ratio of Me O to P 0 is from 1 to 3:1, Me being sodium or potassium, including sodium tripolyphosphate, sodium and potassium pyrophosphate, sodium and potassium orthophosphates and sodium hexametaphosphate, an anhydrous, solid, water-soluble alkali metal silicate wherein the ratio of SiO; to Me O is 0.5 to 3.22:1, Me being sodium or potassium, including sodium mgtasili te, sodium sesquisilicate, sodium orthosih'Eat'e, and" potassium mctasilicate; and sodium carbonate; (B) a caustic material, sodium hydroxide or potassium hydroxide; and (C) a chlorinating agent consisting of granular potassium dichlorocyanurate.

We have found that it is necessary to employ a granular form of the potassium dichlorocyanurate in order to ob- NAMINLE fso 3,166,513 Patented Jan. 19, 1965 tain stable compositions. When a powder form, generally described as having a particle size distribution of by weight through U.S. Standard Screen No. 80 and 80% by weight through U.S. Standard Screen No. 100, is employed, the resulting composition is not sufficiently stable for commercial purposes. On the other hand, if comparatively large particles are used, there is not a sufiiciently rapid dissolution and release of available chlorine upon charging to a dishwashing machine. This is particularly so in home dishwashing machines where there is retention of the detergent composition for only one cycle and for efl'icient operation the available chlorine must be released almost immediately upon introduction of the detergent composition into the machine. Thus, granular potassium dichlorocyanurate having a particle size primarily, i.e., at least about 60% by weight, through U.S. Standard Screen No. 50 and retained on U.S. Standard Screen No. is used in the compositions of our invention. The specific limits of particle size distribution which we have found very efiective are 14% by weight on No. 50 and 9% by weight through No. 100. This granular form of potassium dichlorocyanurate with about 59% available chlorine is commercially available.

In formulating our stable detergent compositions, it is essential that all the ingredients be kept as dry as possible prior to mixing. The ingredients should be of anhydrous grade taken from sealed containers and charged directly to a mixer, such as a conventional commercial ribbon mixer. Furthermore, the chlorinating agent must not be added directly to the caustic.

- n r uilder g and then. -cau's'tic addedtp this ;a u l the ghlorinating 'agenf is added last. In either procedure the caustic'or thechlorinatingagent is first intimately admixed with at least about 30% by weight of builder salts based on the total weight of builder salts in the formulation. The remaining components are added and further mixed for a total period of about three minutes and then packed immediately into sealed containers.

The phosphate material generally comprises from about 15 to about 60% by weight of the final composition and the silicate material generally comprises from about 10 to about 50% by weight of the final composition. The sodium carbonate can be used to replace up to about 30% of the combined phosphate and silicate materials. Thus, the sodium carbonate can comprise up to about 28% by weight of the final composition. The caustic material generally comprises from about 5 to about 30% by weight of the final composition, while the chlorinating agent comprises from about 1 to about 5% by weight of the final composition. Preferably the phosphate material comprises from about 50 to about 55% by weight of the final composition, the silicate material comprises from about 20 to about 25 by weight of the final composition, the caustic material comprises from about 20 to 25% by weight of the final composition, the potassium dichlorocyanurate comprises from about 2 to about 4% by weight of the final composition and no sodium carbonate is employed. In selectingvthe various components for a machine dishwashing formulation it is further preferred that the phosphate material be sodium tripolyphosphate, the silicate material be sodium metasilicate, and the caustic material be sodium hydroxide.

The following examples illustrate in detail our invention. In Examples 1-5, and in Examples 6 and 7 where The chlorinating agent indicated as granular, the potassium dischlorocyanurate was a commercial granular product having a US. Standard Screen analysis of 14% on No. 50 and 9% through No. 100. In Examples 6 and 7 where indicated as powdered, the potassium dichlorocyanurate and the dichlorocyanuric acid had a particle size distribution of about 95% by weight through a US. Standard Screen No. 80 and 80% by weight through a US. Standard Screen No. 100. All of the components used were essentially anhydrous.

EXAMPLE 1 A machine dishwashing detergent formulation of our invention was prepared having the following composition in weight percent.

Percent by weight Sodium tripolyphosphate 51.9 Sodium metasilicate 23.6 Sodium hydroxide 21.3 Potassium dichlorocyanurate 3.2

The above ingredients were added to a laboratory powder mixer in the order shown above and mixed together for three minutes. The mixture was then stored in a sealed glass jar.

EXAMPLE 2 A detergent formulation of our invention was prepared having the following composition in weight percent.

Percent by weight Sodium tripolyphosphate 40.00 Sodium metasilicate 46.00 Sodium hydroxide 10.00

Potassium dichlorocyanurate 4.00

The above ingredients were added to a laboratory powder mixer in the order shown above and mixed together for three minutes. The mixture was then stored in a sealed glass jar.

EXAMPLE 3 A detergent formulation of our invention was prepared having the following composition in weight percent.

Percent by weight Sodium pyrophosphate 30.0 Sodium tripolyphosphate 20.0 Sodium metasilicate 32.0 Sodium hydroxide 15.0

Potassium dichlorocyanurate 3 .0

The above ingredints were added to a laboratory powder mixer in the order shown above and mixed together for three minutes. The mixture was then stored in a sealed glass jar.

EXAMPLE 4 A detergent formulation of our invention was prepared having the following composition in weight percent.

The above ingredints were added to a laboratory powder mixer in the order shown above and mixed together for three minutes. The mixture was then stored in a sealed glass jar.

EXAMPLE 5 A machine dishwashing detergent formulation of our invention was prepared having the following composition.

Lbs. per batch Sodium tripolyphosphate 1100.0

Sodium metasilicate 500.0 Sodium hydroxide (granular) 450.0 Potassium dichlorocyanurate 67.5

Formula- Formulation A 1 tion B (wt. (wt.

percent) percent) Sodium Tripolyphosphate 22.2 30. 0 Light A h 22.2 Dense Ash 22. 2 Sodium Metasilicate (pentahydrate) 40. 0 Ground Caustic 20.0 Sodium pyrophosphate 13. 4 Chlorinated trisodium phosphate 30. 0

2,2561%; biggh'gms. t'etraoxyphthalophenone anhydride per The samples were charged to a standard Hobart Model AM-4 commercial dishwashing machine in an amount sufiicient to provide a concentration of 0.2%. The dishware employed in the tests was soiled with a standard soil load obtained by baking a mixture of oatmeal and India ink on the plates at a temperature of 450 F. After a complete wash and rinse cycle, the dishes were removed from the machine and evaluated on the basis of cleanability value and photometer value. The cleanability value is based on a visual grading in which a value of 33 is given to a dish from which no soil has been removed and a value of 0 is given for one from which all soil has been removed. Thus, the lower the value the greater is the soil removal. The photometer value is a photometric measurement of the film remaining on clear glass due to redeposition of food soil and/or hardwater film. Again, the lower value indicates the cleaner glass. The results of these tests are shown below:

From these data it is observed that the cleaning results of the product of Example 1 are decidedly better than those of either Formulation A, the caustic containing compound, or Formulation B, the chlorine containing compound.

Various samples of the product of Example 5 were evaluated in the field in more than 20 difierent commercial dishwashing machines and over a five month period representing a variety of conditions in relation to water hardness, soil load, operational handling, etc. In all instances the samples of Example 5 were found to be far superior to all other dishwashing compounds against which they were compared. This field study verified and substantiated the evaluation results found in the laboratory.

In addition, samples of other batches made according to Example 5 have been found to have good shelf life and stability as is shown below:

These results were unexpected because previous attempts to formulate sodium hydroxide (caustic) with chlorine containing compounds such as Chlorarnine-T,

5 dichlorodimethyl hydantoin and chlorinated trisodium phosphate had all failed because of the instability of the chlorinating agent in the presence of caustic.

EXAMPLE 6 6 P is from 1 to 3:1, Me being selected from the class consisting of sodium and potassium, (2) from about to about 50% by weight based on the final composition of at least one solid, water-soluble alkali metal silicate wherein the Ten formulations were prepared having the parts by ratio of SiO, to Me O is 0.5 to 3.22:1, Me weight compositions shown in Table 1, each in an amount being s lected from the class consisting of sodium suflicient to provide about 150 grams of formulation. and potassium,

Table 1 Formulation A B C D E F G H I J Sodium tripolyphsophate 51.9 40.01 20 30.5 51.9 51.9 51.9 51.9 Anhydrous sodium metasilicate 23.6 46 32 20 23.6 23.6 23.6 23.6 23.6 23.6 Sodium hydroxide 21.3 10-07 21.3 21.3 21.3 21.3 21.3 Potassium dichlorocyanurate (Granular). 3.2 4.07 3 3. 5 3. 2 3.2 3.2 3.2 'Ietrasodium pyrophsophate Light Sodium Carbonate 26 Potassium hydroxide Diehlorocyanurie acid (powdered) 3. 2 Sodium polyphosphate, Na1O/P1Oi=1 51. 9 Trisodium orthophosphate 51.9 Potassium dichlorocyanurate (powdered). 3.2

In preparing the Formulations A, B, C, D, E, F, G, H and I, the anhydrous constituents except the chlorinating agent were premixed in the order set forth in the table in a laboratory powder mixer for three minutes except for Formulation J in which the caustic was added first, the dichlorocyanurate second, the two admixed for two minutes, the phosphate added next and the metasilicate last with an additional one minute of mixing. With each formulation, immediately after mixing, the chlorinating agent plus the premix to total 10 grams was placed in an individual glass tube, mixed and sealed for use in available chlorine stability tests.

In the available chlorine stability tests, the 10 gram samples were kept at a temperature of 98.6 F. for up to four months before duplicate or triplicate testing using a standard analytical method for determintion of available chlorine.

The available chlorine stability tests showed that after 17-19 days, there was no significant loss of available chlorine in the samples except for Formulaton J in which there was an appreciable loss of available chlorine, that after 53-55 days similar results obtained, that after 81-83 days similar results obtained, but that after 117 to 119 days there were appreciable losses of available chlorine in each of samples, F, I and I. Since the compositions of our invention must be stable for periods ranging from four to six months for commercial purposes, Formulations F, I and J are not satisfactory.

EXAMPLE 7 Additional formulations are made up employing other alkali metal silicates and alkali metal phosphates as shown mixer in the order shown above and mixed together for three minutes after which the mixtures are stored in sealed glass jars.

We claim: 1. A stable detergent composition consisting essentially of:

(A) builder salts in major amount comprising (1) from about 15 to about 60% by weight based on the final composition of at least one alkali (3) from about 0 to about 28% by weight based on the final composition of sodium carbonate;

(B) from about 5 to about 30% by weight based on the final composition of a caustic material selected from the group consisting of sodium hydroxide and potassium hydroxide; and

(C) from about 1 to about 5% by weight based on the final composition of a chlorinating agent consisting of granular potassium dichlorocyanurate having a particle size distribution of at least about 60% by weight through US. Standard Screen No. 50 and retained on US. Standard Screen No. 100; the components of the detergent composition being substantially anhydrous, at least one of the caustic material and the chlorinating agent being first admixed with at least about 30% by weight of builder salts based on the total weight of builder salts in the formulation, and the components being admixed for a period of about three minutes after admixture of the caustic material and the chlorinating agent prior to packaging in sealed containers.

2. The detergent composition of claim 1 in which the alkali metal phosphate is sodium tripolyphosphate, the alkali metal silicate is sodium metasilicate, and the caustic material is sodium hydroxide.

3. The detergent composition of claim 1 wherein the caustic material is first admixed with all of the builder salts and the chlorinating agent is added to the other components last.

f4. A stable detergent composition consisting essentially o (1) from about 50 to about by weight based on the final composition of sodium tripolyphosphate,

(2) from about 20 to about 25% by weight based on the final composition of sodium metasilicate,

(3) from about 20 to about 25% by weight based on the final composition of sodium hydroxide, and

(4) from about 2 to about 4% by weight based on the final composition of a chlorinating agent consisting of granulated potassium dichlorocyanurate having a particle size distribution of at least about by weight through US. Standard Screen No. 50 and retained on US. Standard Screen No. 100; the components of the detergent composition being substantially anhydrous, the chlorinating agent being added to the other components last, and the components being admixed for a period of about 3 minutes after the addition of the chlorinating agent prior to packaging in sealed containers.

5. The detergent composition of claim 4 in which the metal phosphate werein the ratio of Me O to potassium dichlorocyanurate has a particle size distribu- 7 tion of about 14% by weight retained on US. Standard Screen No. 50 and about 9% by weight through US. Standard Screen No. 100.

References Cited by the Examiner UNITED STATES PATENTS 2,035,652 3/36 Hall 252138 2,314,285 3/43 Morgan 252156 2,689,225 9/54 Anderson et a1. 25299 8 3,035,054 5/62 Symes et a1. 25299 3,058,917 10/62 Lintner 25299 OTHER REFERENCES The Chemical Formulary, by Bennett, vol. VI, 1943, Chemical Pub. Co., N.Y., page 482.

Monsanto ACL Technical Bulletin 1-77, Monsanto Chem Co., St. Louis (1959), pages 7 and 14.

JULIUS GREENWALD, Primary Examiner. 

1. A STABLE DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF: (A) BUILDER SALTS IN MAJOR AMOUNT COMPRISING (1) FROM ABOUT 15 TO ABOUT 60% BY WEIGHT BASED ON THE FINAL COMPOSITION OF AT LEAST ONE ALKALI METAL PHOSPHATE WEREIN THE RATIO OF ME2O TO P2O5 IS FROM 1 TO 3:1, ME BEING SELECTED FROM THE CLASS CONSISTING OF SODIUM AND POTASSIUM, (2) FROM ABOUT 10 TO ABOUT 50% BY WEIGHT BASED ON THE FINAL COMPOSITION OF AT LEAST ONE SOLID, WATER-SOLUBLE ALKALI METAL SILICATE WHEREIN THE RATIO OF SIO2 TO ME2O IS 0.5 TO 3.22:1, ME BEING SELECTED FROM THE CLASS CONSISTING OF SODIUM AND POTASSIUM, (3) FROM ABOUT 0 TO ABOUT 28% BY WEIGHT BASED ON THE FINAL COMPOSITION OF SODIUM CARBONATE; (B) FROM ABOUT 5 TO ABOUT 30% BY WEIGHT BASED ON THE FINAL COMPOSITION OF A CAUSTIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND POTASSIUM HYDROXIDE; AND (C) FROM ABOUT 1 TO ABOUT 5% BY WEIGHT BASED ON THE FINAL COMPOSITION OF A CHLORINATING AGENT CONSISTING OF GRANULAR POTASSIUM DICHLOROCYANURATE HAVING A PARTICLE SIZE DISTRIBUTION OF AT LEAST ABOUT 60% BY WEIGHT THROUGH U.S. STANDARD SCREEN NO. 50 AND RETAINED ON U.S. STANDARD SCREEN NO. 100; THE COMPONENTS OF THE DETERGENT COMPOSITION BEING SUBSTANTIALLY ANHYDROUS, AT LEAST ONE OF THE CAUSTIC MATERIAL AND THE CHLORINATING AGENT BEING FIRST ADMIXED WITH AT LEAST ABOUT 30% BY WEIGHT OF BUILDER SALTS BASED ON THE TOTAL WEIGHT OF BUILDER SALTS IN THE FORMULATION, AND THE COMPONENTS BEING ADMIXED FOR A PERIOD OF ABOUT THREE MINUTES AFTER ADMIXTURE OF THE CAUSTIC MATERIAL AND THE CHLORINATING AGENT PRIOR TO PACKAGING IN SEALED CONTAINERS. 